DE69320343T2 - Method for the catalytic conversion of organic materials into a product gas - Google Patents

Abstract

A method for converting organic material into a product gas includes: a) providing a liquid reactant mixture containing liquid water and liquid organic material within a pressure reactor; b) providing an effective amount of a reduced metal catalyst selected from the group consisting of ruthenium, rhodium, osmium and iridium or mixtures thereof within the pressure reactor; and c) maintaining the liquid reactant mixture and effective amount of reduced metal catalyst in the pressure reactor at temperature and pressure conditions of from about 300 DEG C. to about 450 DEG C.; and at least 130 atmospheres for a period of time, the temperature and pressure conditions being effective to maintain the reactant mixture substantially as liquid, the effective amount of reduced metal catalyst and the period of time being sufficient to catalyze a reaction of the liquid organic material to produce a product gas composed primarily of methane, carbon dioxide and hydrogen.

Description

PROCESS FOR CATALYTIC CONVERSION OF ORGANIC MATERIALS INTO A PRODUCT GAS Technical area

This invention relates generally to methods for destroying organic materials, and more particularly to methods for converting organic materials to a product gas composed primarily of methane, carbon dioxide and hydrogen.

State of the art

The amounts and types of organic waste generated have increased significantly in recent years. Many of these organic wastes are hazardous in that they pose significant environmental and health hazards. Hazardous wastes that were previously disposed of using unacceptable methods are continually being discovered at various waste sites. Improved methods for treating and disposing of these hazardous wastes are required to meet environmental standards and to manage these wastes cost-effectively.

Recently, there has been an increased research effort aimed at improving the process used to remediate hazardous materials at problem waste sites. For wastes containing hazardous organic material and water, it is desirable to destroy the organic material so that the water can be reused or released to ground or surface water streams. Thermal technologies currently being developed and applied to destroy organic material include incineration, wet air combustion, and supercritical oxidation.

There are several commercial treatment technologies available for treating water streams with low organic content (< 1000 ppm) using conventional water purification processes, and for treating highly concentrated streams (> 10%) by various expensive processes including solvent extraction and incineration. However, there is a need to be able to treat the currently commercially untreatable concentration ranges (1-5%), as well as other concentration ranges.

Conversion of some organic waste materials, such as those contained in biomass materials, to low Btu fuel gas, carbon monoxide and hydrogen by pyrolysis and substoichiometric combustion at 500ºC to 800ºC and about 101,325-1013,25 kPa (one to ten atmospheres) is known. Studies undertaken to improve such processes have shown that high temperatures with or without catalysts are required to reaction to minimize tar and char formation. Recent interests in organic material conversion have been directed toward producing a medium Btu fuel gas using a steam and/or oxygen gasification environment. These processes would produce a purer carbon monoxide/hydrogen gas mixture that would be used to synthesize methane and other products.

U.S. Patent 4,239,499 to Pfefferte discloses a process for converting a stream containing 25% or more methanol to a product gas. This process, however, has certain limitations on the total water content of the feedstock and requires gas phase reactions. The process as disclosed is limited to a maximum of 1 mole of methanol per 1.5 moles of water due to potential catalytic deactivation, as discussed in column 5, lines 40-49. Another limitation is the viability of the energy required to operate the process. The amount of energy required to vaporize a methanol/water stream is about 60% more than using a liquid stream. Operating a vaporized stream at 350°C requires 2512 kJ/kg (1080 Btu/lb). If the concentration of organic material in the water is held constant, the amount of energy required for a liquid stream at 350ºC is 728 kJ (690 Btu). This path results in a difference of 907 kJ/kg (390 Btu/gallon) and at 0.58 kg/l (8 lb/gallon) this results in an energy saving of about 3270 kJ (3100 Btu) per 3.785 litres (gallon) of waste stream.

U.S. Patent 4,113,446 to Modell et al. discloses a process for converting organic material to a product gas by reaction with water at or above the critical temperature of water and at or above the critical pressure of water to achieve the critical density of water. The reaction is stated to proceed independently of the presence of a catalyst, presumably due to the critical conditions. However, this process also suffers from limitations in the amount of methane produced. This is exemplified by operation with hexanoic acid, where less than one percent methane was produced from about a 2% solution. In view of the small amount of methane production, the energy return on investment of the system appears very unfavorable. For example, using a 10% solution of organic material in water, the amount of energy required to heat and pressurize the system, as disclosed, takes about 2047 kJ/kg (880 Btu/lb) of solution to heat to the critical density of water. However, the gas produced only has a calorific value of about 42.2 kJ (40 Btu).

US-A-4 104 201 discloses a process for steam reforming a desulfurized organic feedstock at a pressure up to 10132.5 kPa (100 atmospheres) and a temperature of 400°C to 600°C using a nickel-ruthenium-alumina catalyst to produce methane, carbon dioxide and hydrogen.

Short description of the drawings

Preferred embodiments of the invention are described below with reference to the following accompanying drawings.

Fig. 1 is a schematic sectional view of an autoclave device for testing the method according to the invention.

Figure 2 is a schematic view of the experimental system used in connection with the present invention.

Figure 3 is a schematic view of a laboratory scale tubular reactor system used in connection with the present invention.

Figure 4 is a graph of crystal size as a function of reaction time when comparing a catalyst used according to the invention with a catalyst from the prior art.

Fig. 5 is a schematic view of a process for catalytic destruction of organic material according to the present invention.

Most preferred embodiments of the invention

According to one aspect of the invention, a method for converting organic material into a product gas comprises:

providing a liquid reactant mixture containing liquid water and organic material in a pressure reactor;

providing an effective amount of a reduced metal catalyst selected from the group consisting of ruthenium, rhodium, osmium and iridium, or mixtures thereof, in the pressure reactor; and

maintaining the liquid reactant mixture and the effective amount of reduced metal catalyst in the pressure reactor at temperature and pressure conditions of from about 300°C to about 450°C and at least 13172 kPa (130 atmospheres), for a period of time, the temperature and pressure conditions being effective to maintain the reactant mixture substantially liquid, the effective amount of reduced metal catalyst and the period of time being sufficient to catalyze a reaction of the liquid organic material to produce a product gas composed primarily of methane, carbon dioxide and hydrogen.

For the purposes of this disclosure, "liquid organic material" means any organic compound or mixture of such compounds that exists as a liquid or gas, or decomposes to a liquid or gas, at a temperature of at least 250°C and a pressure of 50 atmospheres (5066 kPa) or more, and any aqueous solution or any flowable suspension, slurry or sludge containing such a component or mixture. Examples of possible starting materials include waste water streams such as 0.5% hexamethylenediamine in water from nylon production, or 2% or 3% mixed phenols in water from resin production, which would be treated primarily for waste destruction. Other feedstocks, such as cheese water, peat, or high moisture content biomass feedstocks would be treated primarily as energy recovery systems. In some cases, both energy recovery and waste destruction would be achieved. The process can treat liquid organic materials with wide ranges of organic concentration from ppm levels to significantly higher. The process can be used as a method for destroying organic waste or as a method for converting organic feedstocks into an energy source.

Preferably, the liquid organic material and water are supplied to a reactor pressure vessel in the form of an aqueous solution or slurry. If the liquid organic material inherently contains a desired amount of water, such would comprise the liquid organic reaction mixture without requiring the addition of water.

When the organic material comprises multi-carbon compounds, the effective amount of reduced metal catalysts and the time period must be sufficient to catalyze a reaction of the liquid organic material to break the carbon-carbon bonds and to produce a product gas composed primarily of methane, carbon dioxide and hydrogen.

Within the reactor, the organic material and water are preferably maintained at subcritical conditions, such as at a temperature of about 300°C to about 350°C and a pressure of about 13172 kPa (130 atmospheres) to about 20772 kPa (205 atmospheres). Preferably, the pressure within the vessel is just high enough to prevent significant evaporation of water in the reactor; i.e., to keep the reaction mixture substantially liquid. Higher operating pressures, such as those used in supercritical reaction systems, are not required and are considered uneconomical. An optimum condition for conversion is about 350ºC and about 20772 kPa (205 atmospheres), but significant conversions have been achieved at temperatures between 300ºC and 350ºC and at pressures not exceeding 13172 kPa (130 atmospheres).

Thus, a process is disclosed for gasifying reducible organic compounds in water in a substantially liquid state and in the presence of a catalyst at lower temperatures and higher pressures than conventional prior art gasification. The desired result is a product gas of methane, carbon dioxide and hydrogen, as well as a pure water byproduct. The process can be used to treat a wide range of organic materials, including, for example, aliphatic and aromatic hydrocarbons, oxygenated hydrocarbons, nitrogenated hydrocarbons, chlorinated hydrocarbons and carbonaceous feedstocks, such as food production waste and biomass materials, as well as water streams containing such materials.

The catalyst materials of ruthenium, rhodium, osmium and iridium or mixtures thereof may optionally be provided on a support. Exemplary catalyst supports include alumina, such as alumina powder in the form of alpha alumina. Additional catalyst supports include boehmite, zirconia, carbon grains and titania. Reduced ruthenium and rhodium are considered preferred catalysts.

In order to study the organic conversion process of the invention, an experimental reactor system was developed. In the experimental system, an aqueous organic feedstock was converted to innocuous gases consisting mainly of methane, carbon dioxide and hydrogen at low temperatures (300°C to 460°C) and pressures up to 34450 kPa (340 atm). The experimental system was equipped with a sampling system that allowed various samples to be taken during the experiment while the reactor was maintained at the reaction temperature and pressure.

The experimental reaction systems used for this process are shown in Figures 1, 2 and 3. The batch reactor shown in Figures 1 and 2 consists of a 1 liter bolt-sealed autoclave 10 equipped with a belt 25 driven magnetic stirrer 11. The autoclave 10 is of conventional design and is operated with standard electric heating, cooling and stirring equipment supplied with the unit. A stainless steel liner 12 is fitted into the reactor to facilitate product recovery and reactor cleanout. A thermocouple 26 for monitoring temperature was housed within the liner 12. The pressure in the reaction environment was monitored at outlet 27. An outlet 28 was provided for venting exhaust gas. A rupture disk assembly 29 was provided as an overpressure safety relief.

The autoclave 10 is heated with an electric heater 13 that can heat the reaction environment to about 500ºC. A typical time required to heat 300 mL of starting material and catalyst to 350ºC is about 90 minutes. The starting material and catalyst are rapidly mixed in the autoclave 10 by the magnetic stirrer 11. The system is equipped with a cooling coil 14 that is used to cool the reactor contents at the end of each experiment.

Gas samples were drawn from the autoclave 10 through an opening in the wall 16 in the upper part of the reactor. The autoclave 10 and the sampling system are operated remotely after the reactor has been filled with a batch. The sampling system shown in Fig. 2 uses the combination of a manually operated sampling valve 18 and a pressure transducer 20 to collect carefully controlled sample volumes. Typically, the sample loop is filled to a pressure of 3 atmospheres.

The volume of the sampling system is approximately 3.9 ml (2.6 ml sample holding loop plus 1.3 ml dead volume before the sampling valve). The sampling system allows the entire sample loop to be evacuated prior to sampling, thus avoiding contamination from previous samples. The system is equipped with an adsorbent column 22 to collect water or other liquids in the samples. The column 22 is weighed before and after experiments to allow quantitative determination of the mass of water collected. Tests performed to determine the effect of sampling from the system have shown that changes due to sampling are indistinguishable from changes due to experimental error.

In a typical catalytic batch experiment, the desired amount of organic material, catalyst (ground to powder) and required make-up water were weighed and loaded into the stainless steel liner 12. The mixed waste/catalyst slurry in the liner 12 was placed in the autoclave 10 under ambient conditions. The autoclave 10 was sealed, purged with nitrogen, checked for leaks at 7093 kPa (70 atm) with nitrogen and vented until the pressure in the reactor was about 810.6 kPa (8 atmospheres). The nitrogen remaining in the reactor was used as a reference to monitor the enrichment of gaseous products produced during the organic material conversion. This was accomplished by measuring the dilution of the nitrogen in the gas samples taken at regular intervals once the reactor reached the desired reaction temperature. The reactor was then held at this temperature for about one hour. Pressures in the system ranged from about 13679-37997 kPa (135-375 atm), depending on the reaction temperature chosen and the amount of gas produced.

At the end of each experiment, cooling water was flushed through the reactor's internal cooling coil 14 and the contents were brought to a temperature of 200°C in about 5 minutes. After the autoclave 10 was completely cooled, the gas product was drained through a volumetric meter and analyzed by conventional methods using a gas chromatograph 24. The liquid contents of the reactor were removed, measured and analyzed for later analysis by conventional methods including gas chromatography and chemical oxygen demand (COD). Solids, which were primarily the catalyst, were filtered from the liquids, dried, weighed and their carbon content determined.

The conversion was carried out by subtracting the amount of COD still present in the liquid reactor product from the COD of the aqueous waste fed into the reactor Carbon conversions to gas were calculated based on the amount of gas produced and its composition.

Ruthenium, rhodium, platinum and palladium were tested in the batch reactor as possible catalysts in a reaction system at 350ºC and 20772 kPa (205 atmospheres) using a feedstock of 10 wt% para-cresol in water. These results are summarized below in Table 1. TABLE 1

* Suboxide form, not completely reduced to metal

** reduced and dried

NA = not analyzed

The percentage numbers under the catalyst column reflect the amount by weight of the elemental metal with respect to the respective supports shown. Subsequent analysis determined that the 1% and 0.5% ruthenium and the later 1% rhodium reported were not fully reduced but were in an oxide form. As these results demonstrate, the oxidized metals exhibit low catalytic activity for both carbon gasification and methanation. The numbers in the carbon on catalyst column reflect the amount of carbon found on the catalyst, indicating a buildup that may shorten the life of the catalyst or, alternatively, indicate carbon intermediates that have not yet been fully converted to one of the product components. Tests were also conducted with copper, molybdenum, tungsten, chromium and zinc metals, but these also showed very low levels of catalytic activity.

The above results clearly show significant carbon conversion and production of methane, carbon dioxide and hydrogen using ruthenium and rhodium as catalysts. Osmium and iridium are also expected to be useful catalysts in accordance with this invention since they have similar chemical properties and similar catalytic activity for CO methanation. However, they are less common and probably much more expensive to use as catalysts.

Previous studies have shown that reduced nickel metal is a useful catalyst for reducing organic material in liquid water solution or slurry, such as disclosed in our co-pending U.S. Patent Application Serial No. 07/168,470 entitled "Method For Catalytic Destruction Of Organic Materials," and also in our U.S. Patent No. 5,019,135, "Method for the conversion of Lignocellulosic Materials," which are incorporated herein by reference. Long-term operating data comparing ruthenium versus nickel have been developed and are presented below in Table 2. TABLE 2

The flow reactor system used for these tests is shown in Fig. 3. In particular, a reciprocating positive displacement pump 51 with a packed piston was used to feed the system. The system piping included 1.27 cm (0.5 in.) OD (0.165 cm (0.065 in.) wall thickness) 304 stainless steel tubing at the outlet of the pump 51. The pump inlet piping was 1.27 cm (0.5 in.) OD (0.09 cm (0.035 in.) wall thickness) 304 stainless steel pipes. All valves and valve trims (except the pressure control valve) were also made of stainless steel.

The tubular reactor 52 shown was a 5.08 cm (2-in.) O.D. x 2.54 cm (1-in.) LD. x 1.83 m (72-in.) 304 stainless steel tubular reactor. The threaded end caps contained hold-down bolts for the 304 stainless steel end fittings and O-ring seals. The vessel was heated by a three-section ceramic furnace 53. The temperature was monitored on the outer wall and in the center of the catalyst bed at three points along the length of the reactor.

Once the products left the reactor 52, they were passed through a 60-micron filter 54 and cooled in a primary condenser 55 and depressurized before entering the separator. The pressure in the reactor was controlled by either a control valve 56 or a dome-loaded back pressure regulator. The lines to the reactor were 0.635 cm (0.25-in.) O.D. tubing with thick wall (0.124 cm) (0.049 in.) before depressurization and thin wall (0.089 cm) (0.035 in.) afterward. The valve 56 contained a 0.238 cm (3/32-in.) orifice. The valve stem and seat were made of stellite. Excessive wear of the stellite trims resulted in the replacement of the valve with the back pressure regulator. Both systems functioned adequately when they were in good condition.

After depressurization, phase separation was performed in a vertical separator 60 with a 60.96 cm (24 in.) x 1.27 cm (0.5 in.) diameter pipe. Most of the liquid products were removed via the bottom of the separator through the condensation pot 57 and into the liquid collection tank 58. To eliminate water carryover into the gas analysis system, a float condensation pot 63 was placed after the secondary condenser, as was a T-type filter 61 with a 0.02 µm hollow fiber membrane filter. The float trap condensate product from both drains was collected in a liquid collection tank attached to an electronic measuring cell.

A liquid collection loop or line 59, upstream of the separator, allowed the recovery of small volumes of liquid product before it was discharged into the condensate collection vessel. The samples were considered representative of the reactor contents.

The data acquisition and control (DAC) system used in the CRS was a hybrid personal computer (PC) based system using discrete data acquisition units and single-loop process controllers communicating with a central PC via an RS232 serial interface. The PC was used during the experiments to monitor the procedure, calibrate instruments and record data to an ASCII file for later analysis. A custom-written program was used to coordinate these activities. Distributed single-loop control by individual controllers was chosen to provide additional security in the event of a DAC system failure and to reduce the amount of DAC software required. allocated computational overhead. Non-control sensors such as thermocouples and the gas mass flow meter were monitored using a data acquisition unit. The unit processed all raw signals into engineering units before sending the data to the PC for recording. Using this system allowed a number of data channels to be transmitted using a single RS232 serial port and allowed additional computational overhead to be shifted from the main PC.

The product gas flow rate was measured using a thermal conductivity mass flow sensor. The unit was calibrated to nitrogen gas (0-2 SLPM), but actual mixed gas flow rates could be calculated based on known calibration factors and gas composition. The product gas also passed through a wet meter 62 to determine total gas flow.

The tubular reactor was sealed once the specified amount and type of catalyst had been charged into the reactor vessel. After the reactor was sealed, the system was pressure tested using nitrogen. The purge gas was vented from the system and the reactor was refilled with hydrogen. The catalyst bed was heated overnight in hydrogen to ensure that the metal catalyst was reduced.

Once the system was warmed to operating temperature, the feedstock was pumped into the reactor system and the system was finally pressurized. The feed rates, temperatures and pressures were controlled throughout the experiment while the products were recovered and quantified.

To terminate an experiment, the feed pump was stopped and the reactor furnaces were turned off. Typically, the reactor was left pressurized overnight while it cooled down.

As can be seen in Table 2, the catalytic activity of nickel decreased significantly after two days, while that of ruthenium maintained its activity at 10 days, and certainly more, for some different starting materials.

The stability of nickel and ruthenium crystals at operating conditions was investigated by X-ray diffraction measurements and is shown in Fig. 4. There, the metal crystal size is shown as a function of time at reaction conditions for the indicated catalyst. The Raney nickel catalyst was unsupported, while the two other methanation and hydrogenation Ni catalysts were supported on magnesium silicate and alumina supports, respectively. The ruthenium shown was supported on alumina. As can be seen in Fig. 4, the change in nickel crystal size varies greatly between an alumina supported catalyst, a magnesium silicate supported catalyst and an unsupported one. It is clear It is undesirable for the catalyst crystal size to increase with time, as this reduces the available surface area for catalytic activity for a given amount of catalyst. Figure 4 shows that the ruthenium catalyst actually reduces its crystal size with time, thus potentially increasing the catalytic activity for a given amount of catalyst.

Rhodium, osmium and iridium are all expected to have long-term stability similar to ruthenium due to their noble metal classification. Although ruthenium has been shown to have significantly long-term stability of at least an order of magnitude greater than nickel, the cost difference between the two metals is large. Even with the greater stability of ruthenium, a low-cost catalyst may not be available. In such a case, a mixture of Ni with other described metals may be preferred. In such cases, and as described in our U.S. Patent No. 5,019,135 and our co-pending U.S. Patent Application Serial No. 07/168,470, reduced nickel in an effective amount exhibits catalytic activity on its own. The use of less than 1 wt% ruthenium in the reduced nickel can stabilize the reduced nickel metal sufficiently so that crystal growth and the resulting loss of active surface are no longer a problem as they were when nickel was used alone. In this case, Ru would act as a spacer to limit crystal growth. For example, gold has been used as a spacer in various catalyst applications.

Useful catalyst support materials were also identified by batch reactor testing. The most conventional supports, consisting of silicates and refractory cements, were found to be chemically and physically unstable in the reaction environment of the present process. Tests with various aluminas indicate that boehmite is the thermodynamically favored form under these conditions, since the δ, η, and γ forms all react to form boehmite. Only the α-alumina appears to resist hydration at reaction conditions. Other potential supports were tested, including carbon grains, and titania and zirconia powders in tablet form. All exhibit relatively good chemical stability at the reaction conditions. The metal-loaded carbon showed reaction of the carbon with the water to produce gases, which may limit its usefulness for extended periods of time. Neither titania nor zirconia were hydrogenated and zirconia in particular retained strong physical integrity.

The amount of water present should be sufficient to supply hydrogen as necessary to promote the formation of product gases such as CH₄. If the organic material can be represented as CmHnOgNjXr, the liquid water should be present in the reactant mixture in an amount equal to or in excess of the molar amount according to the following formula:

wherein "X" is a halogen, "m" and "n" are each greater than or equal to one, and "g", "j" and "r" are each greater than or equal to zero.

Energy efficiency of the process

As noted in the discussion of the prior art, other proposed systems suffer from the profitability of the total amount of energy required to run the process and the total amount of energy produced by the process. This is exemplified in the following example.

To supply vaporized feedstock to a reactor, as described in U.S. Patent No. 4,239,499, the amount of energy required to vaporize a methanol/water stream is about 60% more than that required for a liquid stream. To operate a vaporized stream at 350°C and 10342 kPag (1500 psig), 2512 kJ/kg (1080 Btu/lb) is required. Using the process of our invention, when a concentration of organic material and water is held substantially constant, a liquid stream at 350°C and 20684 kPag (3000 psig) requires 728 kJ (690 Btu) to heat and pressurize. This results in a difference of 945 kJ/kg (390 Btu/lb), and at 0.96 kg/l (8 lb/gallon) this results in a difference of about 3270.5 kJ (3100 Btu) per 3.785 liter (gallon) of reactant flow. In addition, the use of higher pressure and a denser reaction medium (while preferably maintaining subcritical fluid conditions) allows the use of smaller reactor sizes for equivalent throughputs.

Using a process described in U.S. Patent No. 4,113,446 and 10% organic material (hexanoic acid) in aqueous solution, the amount of energy required by the system is disclosed to be 2046.7 kJ/kg (880 Btu/lb) of solution to heat and pressurize to the critical density of water to produce a gas with a heating value of only 42.2 kJ (40 Btu). In the process of the present invention, the amount of energy required for 350°C and 20684 kPag (3000 psig) is 1605 kJ/kg (690 Btu/lb) of solution, with the gas having a heating value of 3093 kJ/kg (1330 Btu/lb) of solution. This results in a net value of 1488 kJ/kg (640 Btu/lb) or about 5380 kJ (5100 Btu) per 3,785 litres (gallon) of waste stream.

Preferred method for larger scale conversion

Fig. 5 shows an apparatus for a preferred embodiment of the process of the invention. The organic material in an aqueous solution is pumped to 20265 kPa (200 atm) by a high pressure pump 30 and then passed through a heat exchanger 32 to preheat the waste stream to 350°C. It is believed that the Most of the preheating can be supplied by heat exchange with the reactor effluent. Required auxiliary heat can be supplied by an external heat source or by burning the product gas in a heater 34. If the carbon content of the waste stream is 1 wt.% or more, it should provide sufficient fuel gas to heat the process.

After preheating, the liquid reactant mixture is fed to a pressure reactor 36 for converting the organic material into a product gas. After passing through heat exchanger 32 to preheat the incoming liquid reactant mixture, the effluent from reactor 36 is separated into constituent components, such as in separator 38 or by other conventional gas processing or recovery techniques.

In a continuous system where the product gas can be removed or vented as it is generated, the pressure in the system can be reduced. To minimize the energy requirements of the process, the pressure must be high enough to maintain the reactant mixture essentially as a liquid. Based on the enthalpy and specific volume of water at various conditions, it is believed that the optimum operating conditions are 300ºC to 350ºC, and at a pressure sufficient to maintain the reactant mixture essentially as a liquid to avoid energy loss by evaporation of the water, as would be required in supercritical operation.

Claims (9)

1. A process for converting organic material into a product gas, comprising: (a) providing a liquid reactant mixture containing liquid water and liquid organic material in a pressure reactor; (b) providing an effective amount of a reduced metal catalyst selected from the group consisting of ruthenium, rhodium and iridium, or mixtures thereof, or a member of the group additionally containing an effective amount of reduced nickel, in the pressure reactor, and (c) maintaining the liquid reactant mixture and the effective amount of reduced metal catalyst in the pressure reactor at conditions of temperature and pressure of from about 300°C to about 450°C and at least 13172.25 kPa (130 atmospheres (atm)) for a period of time at conditions of temperature and pressure effective to maintain the water in the reactant mixture substantially liquid, the effective amount of reduced metal catalyst and the period of time being sufficient to catalyze a reaction of the liquid organic material to produce a product gas composed primarily of methane, carbon dioxide and hydrogen. 2. A process for converting organic material into a product gas according to claim 1, wherein the organic material comprises multi-carbon bonds. 3. A process for converting organic material to a product gas according to claim 1 or 2, wherein the temperature conditions are from about 300°C to about 350°C and the pressure conditions are from about 13172.25 kPa (130 atm) to about 20771.6 kPa (205 atm). 4. A process for converting organic material into a product gas according to claim 1 or 2, wherein the reduced metal catalyst is supported on a carrier selected from the group consisting of alumina, α-alumina, boehmite, titania, zirconia and carbon. 5. A process for converting organic material into a product gas according to claim 1, wherein (a) the reduced metal catalyst is selected from the group consisting of reduced ruthenium or rhodium (b) the temperature conditions are from about 300ºC to about 350ºC; and (c) the pressure conditions are from about 13172.25 kPa (130 atm) to about 20771.6 kPa (205 atm) and the reduced metal catalyst is supported on a carrier comprising alumina. 6. A process for converting organic material into a product gas according to claim 1, wherein (a) the reduced metal catalyst is selected from the group consisting of ruthenium and rhodium or mixtures thereof; and (b) the reduced metal catalyst is supported on a support selected from the group consisting of titania, zirconia and carbon. 7. A process for converting organic material into a product gas according to claim 1 or 2, wherein the organic material comprises CmHnOgNjXr and the liquid water is present in the reactant mixture in an amount equal to or in excess of the molar amount according to the following formula: where "X" is a halogen, "m" and "n" are each greater than or equal to one, and "g", "j" and "r" are each greater than or equal to zero. 8. A process for converting organic material into a product gas according to claim 7, wherein (a) the temperature conditions are from about 300ºC to about 350ºC; and (b) the pressure conditions are from about 13172.25 kPa (130 atm) to about 20771.6 kPa (205 atm). 9. A process for converting organic material comprising multi-carbon compounds into a product gas according to claim 2, wherein (a) the reduced metal catalyst is selected from the group consisting of ruthenium and rhodium or mixtures thereof; (b) the temperature conditions are from about 300ºC to about 350ºC; and (c) the pressure conditions are from about 13172.25 kPa (130 atm) to about 20771.6 kPa (205 atm); and (d) the reduced metal catalyst is supported on a support comprising alumina.